NOTE: As their name suggests hints are not exactly Assassin's Creed 3 cheats, and are usually just simple (but very useful) tips on how you can unlock secret level, features, find hidden areas and such. Hopefully these will make playing Assassin's Creed 3 even more entertaining.

Achievements
Complete each achievement to get the allotted gamerscore.

A Complete Set (20): See all the optional characters settled at the Homestead.
Abstergo Entertainment (10): Reach level 20 in the multiplayer mode.
All Washed Up (40): Complete all Naval Missions aboard the Aquila.
An Extraordinary Man (10): Complete the Encyclopedia of the Common Man.
Blowing in the Wind (20): Retrieve every page for one of Ben Franklin's Almanacs.
Bring Down the House (20): Explore Fort Wolcott.
By Invitation Only (20): Be invited to join a Club.
Caged Wolf (20): Complete Sequence 8.
Circus Act (10): Kill 15 guards with a single cannon shot.
Completionist (50): Complete ALL progress tracker grid entries.
Coureur des Bois (10): Exchange undamaged pelts at all different general stores.
Criss Cross (20): Complete Present - Skyscraper.
Daddy Dearest (20): Complete Present - Stadium.
Difficult End (20): Complete Sequence 11.
Entrepreneur, not Pirate! (20): Complete all 12 Privateer Contracts.
Eye Witness (10): Witness a predator killing an enemy.
Fin (30): Complete each of the epilogue missions unlocked after the credits roll.
Grim Expectations (20): Complete Sequence 10.
Head in the Cloud (20): Find all pivots and sync the Animus to the Cloud.Heroes are Born (20): Complete Sequence 4.
House Party (10): Recruit any of the Artisans and see them settled on the Homestead.
How D'ya Like Them Apples (20): Complete Sequence 3.
Hunter/Killer (20): Reach sequence 10 in a map on Wolfpack multiplayer mode.
In Good Standing (30): Complete all challenges for any of the Clubs.
Jager Bomb (20): After becoming fully Notorious, kill 10 Jagers before losing your notoriety.
Kidd Gloves (30): Uncover the mystery of Oak Island.
Magna cum Laude (20): Have a Trainee reach the Assassin Rank.
Man of the People (20): Liberate all districts in Boston OR New York.
Monopoly Man (10): Send a convoy to Boston, New York and the Frontier.
Multitasking (20): Complete 50% of the Progress Tracker entries.
Mystery Guest (20): Complete Sequence 1 & 2.
No Good Deed Goes Unpunished (20): Open the Temple Door and learn Desmond's fate.
Original Gamer (20): Win a game of Fanorona, Morris and Bowls on the Homestead.
Patent Not Pending (10): Craft one of Franklin's inventions to decorate your Manor.
Perfectionist (50): Complete 100% of all main mission constraints.
Personalized (10): Customize your multiplayer Profile and Character.
Predator (10): Hang 5 enemies by using rope darts.
Prince of Thieves (10): Loot a convoy without killing any of its guards.
Rude Awakening (10): Re-Enter the Animus.
Spit Roast (20): Perform a double assassination using a musket.
Tea is for Englishmen (20): Complete Sequence 6.
The Day the Templars Cried (20): Complete Sequence 5.
The End is Nigh (20): Complete Present - Abstergo.
The Sum of Truth (50): Complete Sequence 12.
The Truth Will Out (20): Unlock a hacked version of one of the Abstergo videos in the story quest.
The Whites of Their Eyes (20): Complete Sequence 7.
Tumblehome (10): Upgrade the Aquila.
Two if by Sea (20): Complete Sequence 9.
Whit's fur ye'll no go by ye! (10): Block a firing line 5 times by using a human shield.
Winning Team (20): Be on the winning team at the end of a multiplayer game session.

Assassin Turkey
At any point beyond Sequence 6, return to the Davenport Homestead and, from the front door, walk around the right side of the manor and hide around the corner at the back. Whistle, and a turkey will appear nearby. Approach it and press up, up, down, down, left, right, left, right, B, A to feed it. This will result in the turkey donning an Assassin's hood and following Connor around.